Hospitalization

Recently my nine year old has been having very violent outbursts where he is hitting kicking, bitting throwing things etc. We have had to physically restrain him multiple times a week. He is getting stronger and bigger and I am concerned for the safety of my 16 month old because when my older son is in one of these fits he doesn't care about anyone or anything. He had never threatened the baby but he has threatened to harm myself and my boyfriend as well as himself. I am concerned that he is going to throw something and it may hit the baby. I am really at my wits end and don't know what to do. He has been hospitalized 2 times about 2 years ago. I really don't want to have to go this route again but we are very concerned about everyones safety including his. Any input on this situation would be greatly appreciated.